"Violence is never an appropriate response to free speech, and we support the rights of people everywhere to free expression and peaceful protest", State Department spokeswoman Heather Nauert said.

Video shot by Voice of America, which quickly went viral, shows pro-Erdogan forces breaking through a police line to kick and punch the pro-Kurd protesters. Two men were bloodied from head wounds as bystanders assisted dazed protesters.

President Recep Tayyip Erdoğan and his American counterpart Donald Trump seem to have reached an understanding that they agree to disagree especially on the active USA support to the PKK-linked Syrian Kurdish militants which Ankara regards as terrorists.

The Turkish Embassy said in a statement the protesters were affiliated with the outlawed PKK.

"Just previous year, when Erdogan was back in the States for a summit on nuclear security, at Brookings, outside Brookings, [in Washington, D.C.], there were similar protests and similar unseemly scenes of clashes along Massachusetts Avenue".

Washington Police Chief Peter Newsham told a news conference on Wednesday police had a good idea of most of the assailants' identities and were investigating with the Secret Service and State Department.

One of the men arrested, Jalal Kheirabadi, told Reuters he was being beaten by three or four people when a D.C. police officer accused him of assault.

Turkey's foreign minister says the country will continue to fight Syrian Kurdish militants, and he has relayed this position to the United States, which considers them a key ally against the Islamic State group.

"They did not say anything negative about this issue and treated it with understanding".

Police said they were in "the preliminary stages" of an investigation into the incident.

"We told them. we do not regard your cooperation with a terrorist group in Raqqa as healthy", Erdogan was cited as saying, but he said he expected a role for Turkey in Syria.

"Groups affiliated with the PKK, which the USA and Turkey have designated as a terrorist organization, gathered yesterday without permit in Sheridan Circle in the immediate vicinity of the Ambassador's Residence, while the President of Turkey was visiting the Residence".

"The violence and injuries were the result of this unpermitted, provocative demonstration", the statement said.

"The demonstrators began aggressively provoking Turkish-American citizens" that had gathered to greet Erdogan, the statement read.

Washington Mayor Muriel Bowser and five Republican senators, including John McCain of Arizona and Marco Rubio of Florida, also condemned the assault. It said they chanted anti-Erdogan slogans, and that Erdogan's team moved in to disperse them because "police did not heed to Turkish demands to intervene". His appearance at the Brookings Institution during the 2016 Nuclear Security Summit was marred when his security detail roughed up demonstrators and tried to eject "undesired" journalists. "Because we have no time to lose", he said. "I'm scared now too, because I don't know how it will affect my life here in the United States", said Tankan, who lives in Arlington, Virginia.